Niese, the reacquired left-hander inserted into the rotation last week to replace Logan Verrett, felt a “pop” in his knee as he delivered a first-inning curveball to Brandon Moss, and was removed moments later after surrendering a single.

“It progressively got worse and worse,” Niese, who recorded just one out Tuesday and allowed a pair of walks in addition to Moss’ single, told reporters following his club’s 7-4 victory at Busch Stadium. “Every pitch, there was just a sharp, shooting pain down my leg. … I’ve got to get it fixed. I can’t keep going out there like that.”

Niese, who joked that he “leads the league in MRIs,” noted that he has been dealing with various levels of discomfort in his left knee since June, back when he was still a member of the Pittsburgh Pirates. Through 121 innings split between Pittsburgh and New York this season, the 29-year-old owns a 5.50 ERA with a 1.58 WHIP while uncorking a league-worst 11 wild pitches.

With Matz still hurting and Verrett toiling in the minors, Niese’s rotation spot could go to rookie right-hander Robert Gsellman. Manager Terry Collins hinted as such after the 23-year-old fired 3 2/3 scoreless innings in his MLB debut Tuesday upon taking over for Niese in the bottom of the first.

Now 3 1/2 games back of the Cardinals for the second National League wild-card spot, the Mets’ once vaunted rotation has scuffled of late, managing a 4.78 ERA with a 1.41 WHIP over the last two weeks.